US5735484A - Helicopter skid - Google Patents

Helicopter skid Download PDF

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Publication number
US5735484A
US5735484A US08/622,548 US62254896A US5735484A US 5735484 A US5735484 A US 5735484A US 62254896 A US62254896 A US 62254896A US 5735484 A US5735484 A US 5735484A
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US
United States
Prior art keywords
wall
web
skid
tube
along
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired - Lifetime
Application number
US08/622,548
Other languages
English (en)
Inventor
James Bradley
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Dart Aerospace Ltd
Original Assignee
Nosterra Holdings Ltd
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Nosterra Holdings Ltd filed Critical Nosterra Holdings Ltd
Assigned to NOSTERRA HOLDINGS LTD. reassignment NOSTERRA HOLDINGS LTD. ASSIGNMENT OF ASSIGNORS INTEREST (SEE DOCUMENT FOR DETAILS). Assignors: BRADLEY, JAMES
Priority to US08/622,548 priority Critical patent/US5735484A/en
Priority to DE69705786T priority patent/DE69705786T2/de
Priority to EP97908092A priority patent/EP0828655B1/fr
Priority to CA002222184A priority patent/CA2222184C/fr
Priority to AU20196/97A priority patent/AU2019697A/en
Priority to PCT/CA1997/000194 priority patent/WO1997035762A1/fr
Priority to AT97908092T priority patent/ATE203478T1/de
Publication of US5735484A publication Critical patent/US5735484A/en
Application granted granted Critical
Assigned to DART AEROSPACE LTD. reassignment DART AEROSPACE LTD. ASSIGNMENT OF ASSIGNORS INTEREST (SEE DOCUMENT FOR DETAILS). Assignors: NOSTERRA HOLDINGS LTD.
Assigned to DART AEROSPACE LTD reassignment DART AEROSPACE LTD ASSIGNMENT OF ASSIGNORS INTEREST (SEE DOCUMENT FOR DETAILS). Assignors: NOSTERRA HOLDINGS LTD
Anticipated expiration legal-status Critical
Assigned to BARINGS FINANCE LLC, AS COLLATERAL AGENT reassignment BARINGS FINANCE LLC, AS COLLATERAL AGENT SECURITY INTEREST (SEE DOCUMENT FOR DETAILS). Assignors: DART AEROSPACE LTD.
Expired - Lifetime legal-status Critical Current

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Classifications

    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B64—AIRCRAFT; AVIATION; COSMONAUTICS
    • B64C—AEROPLANES; HELICOPTERS
    • B64C25/00—Alighting gear
    • B64C25/32—Alighting gear characterised by elements which contact the ground or similar surface 
    • B64C25/52—Skis or runners
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B64—AIRCRAFT; AVIATION; COSMONAUTICS
    • B64C—AEROPLANES; HELICOPTERS
    • B64C25/00—Alighting gear
    • B64C25/32—Alighting gear characterised by elements which contact the ground or similar surface 
    • B64C2025/325—Alighting gear characterised by elements which contact the ground or similar surface  specially adapted for helicopters

Definitions

  • This invention relates to skid type landing gear for helicopters.
  • the invention comprises a helicopter skid having a wall defining an elongated generally cylindrical tube, and a web extending vertically along the longitudinal axis of the skid between a bottom portion and a top portion of the wall.
  • the invention comprises such a skid wherein the top and the bottom portions of the wall have a tapering thickness with maxima where the web meets the top and bottom portions and wherein the thickness tapers with angular displacement along the wall away from the vertical axis of the web.
  • the invention further comprises a thickened portion along each of the sides of the tube.
  • the invention further comprises a plurality of horizontal members extending along the horizontal axis of the tube between the sides of the tube at regular intervals throughout the longitudinal extent of the tube.
  • FIG. 1 is a cross-sectional view of a tubular helicopter skid according to the prior art
  • FIG. 2 is a cross-sectional view of a helicopter skid according to a first embodiment of the invention
  • FIG. 3 is a cross-sectional view of the structure in FIG. 1 under a certain bottom load condition wherein stress measurements are indicated by reference to Table I below;
  • FIG. 4 is a cross-sectional view of the structure in FIG. 2 under the same load condition as in FIG. 3 wherein stress measurements are indicated by reference to Table I below;
  • FIG. 5 is a cross-sectional view of a helicopter skid according to the preferred embodiment of the invention.
  • FIG. 6 is a cross-sectional view of the structure in FIG. 1 under a certain side load condition wherein stress measurements are indicated by reference to Table I below;
  • FIG. 7 is a cross-sectional view of the structure in FIG. 2 under the same load condition as in FIG. 6 wherein stress measurements are indicated by reference to Table I below;
  • FIG. 8 is a cross-sectional view of the structure in FIG. 5 under the same load condition as in FIG. 6 wherein stress measurements are indicated by reference to Table I below.
  • FIG. 1 there is shown a typical prior art helicopter skid 10.
  • the skid consists of an elongated tube 11.
  • the top portion 12 and the bottom portion 14 of the tube are thickened relative to the side portions 16 and 18 so as to enable the skid to substantially retain its integrity when the skid hits rocks or sharp objects upon landing and to distribute the stresses throughout the skid.
  • such prior art structure is not particularly effective in distributing the stress which the skid suffers upon landing.
  • the skid is susceptible to relatively high stresses particularly at the bottom portion 14 and consequently it is still relatively susceptible to puncturing.
  • FIG. 2 is a cross-sectional view of a skid according to a first embodiment of the invention.
  • the skid consists of a straight, elongated, cylindrical tube having a wall 20 made of a suitable material such as aluminium alloy.
  • a vertical web 22 extends substantially throughout the length of the tube along the tube's longitudinal axis between top apex on portion 24 and bottom apex on portion 26.
  • Top portion 24 and bottom portion 26 of the wall include a gradual and tapered thickening which is at its maximum along the vertical axis of web 22 where the web meets the top and bottom portions 24 and 26, and the thickness tapers with angular displacement along the wall away from the vertical axis.
  • Web 22 is preferably formed integrally with the thickened top and bottom portions 24 and 26 but the principle of the invention applies in the case of an insertable web-like piece which would be inserted or otherwise placed within the tube in sufficient contact with the thickened walls of the top and bottom portions to distribute the stresses therethrough.
  • Thicker portions 28 and 30 of the wall 20 are provided along the sides of the tube. Without portions 28 and 30, the structure of FIG. 2 would have a 10% increase in vertical bending stiffness and a 7.5% decrease in horizontal bending stiffness as compared to the structure of FIG. 1. The addition of portions 28 and 30 provide additional rigidity against bending in the horizontal plane. Portions 28 and 30 are also useful to provide a surface for connecting the cross bolts used to attach the landing struts to the skid.
  • FIG. 5 illustrates the preferred embodiment of the skid according to the invention.
  • horizontal members 32 extend horizontally between the thickened portions 28 and 30 of the skid at regular intervals throughout the longitudinal extent of the skid.
  • Horizontal members 32 are preferably hollow tubes formed integrally with portions 28 and 30 of the wall and which pass through suitable apertures in the web 22.
  • the maximum stresses having a magnitude of about 165,000 psi occur in the region next to the thicker portion on the side that the load was applied.
  • the maximum stresses having a magnitude of only 70,000 psi occur in both the region next to the thicker portion on the side that the load was applied and the region of web 20 next to the top portion of the wall. It will therefore be appreciated that the structure according to the preferred embodiment also provides a substantially improved stress distribution characteristic when a load is applied to the side of the skids.

Landscapes

  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Aviation & Aerospace Engineering (AREA)
  • Earth Drilling (AREA)
  • Toys (AREA)
  • Body Structure For Vehicles (AREA)
  • Fittings On The Vehicle Exterior For Carrying Loads, And Devices For Holding Or Mounting Articles (AREA)
  • Gears, Cams (AREA)
  • Braking Arrangements (AREA)
  • Motorcycle And Bicycle Frame (AREA)
  • Investigating Strength Of Materials By Application Of Mechanical Stress (AREA)
US08/622,548 1996-03-25 1996-03-25 Helicopter skid Expired - Lifetime US5735484A (en)

Priority Applications (7)

Application Number Priority Date Filing Date Title
US08/622,548 US5735484A (en) 1996-03-25 1996-03-25 Helicopter skid
AT97908092T ATE203478T1 (de) 1996-03-25 1997-03-21 Kufenlandegestell für einen hubschrauber
EP97908092A EP0828655B1 (fr) 1996-03-25 1997-03-21 Patin d'helicoptere
CA002222184A CA2222184C (fr) 1996-03-25 1997-03-21 Patin d'helicoptere
AU20196/97A AU2019697A (en) 1996-03-25 1997-03-21 Helicopter skid
PCT/CA1997/000194 WO1997035762A1 (fr) 1996-03-25 1997-03-21 Patin d'helicoptere
DE69705786T DE69705786T2 (de) 1996-03-25 1997-03-21 Kufenlandegestell für einen hubschrauber

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
US08/622,548 US5735484A (en) 1996-03-25 1996-03-25 Helicopter skid

Publications (1)

Publication Number Publication Date
US5735484A true US5735484A (en) 1998-04-07

Family

ID=24494594

Family Applications (1)

Application Number Title Priority Date Filing Date
US08/622,548 Expired - Lifetime US5735484A (en) 1996-03-25 1996-03-25 Helicopter skid

Country Status (7)

Country Link
US (1) US5735484A (fr)
EP (1) EP0828655B1 (fr)
AT (1) ATE203478T1 (fr)
AU (1) AU2019697A (fr)
CA (1) CA2222184C (fr)
DE (1) DE69705786T2 (fr)
WO (1) WO1997035762A1 (fr)

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US6244538B1 (en) * 1999-05-19 2001-06-12 Bell Helicopter Textron Inc. Stiffness de-coupled skid landing gear
US20150336661A1 (en) * 2012-06-26 2015-11-26 Bell Helicopter Textron Inc. Lightweight helicopter skid shoes
US10858091B2 (en) 2017-08-11 2020-12-08 Bell Helicopter Textron Inc. Helicopter skid landing gear

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2539817A (en) * 1946-10-31 1951-01-30 Francis J Ditter Aircraft ski
US5211359A (en) * 1991-05-06 1993-05-18 Aerospatiale Societe Nationale Industrielle Landing gear for aerodynes, with crosspieces in composite material
US5358201A (en) * 1993-02-05 1994-10-25 Brown Sr Louis S Vehicle skid assembly
US5462242A (en) * 1993-11-05 1995-10-31 Bell Helicopter Textron Inc. Helicopter landing gear assembly

Family Cites Families (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR531588A (fr) * 1922-01-17
DE521248C (de) * 1926-10-01 1931-03-19 D Aviat Louis Breguet Sa Des A Zweiteiliges Rohr mit einer ebenen Mittelwand, deren Raender zusammen mit denen der Rohrteile gefalzt sind, insbesondere fuer den Flugzeugbau
GB303058A (en) * 1927-12-27 1930-01-22 Dornier Metallbauten Gmbh Improvements in or relating to hollow metallic supports or beams
FR1272208A (fr) * 1960-10-14 1961-09-22 Bolkow Entwicklungen Kg élément élastique en matière synthétique et en forme de barre permettant une forte absorption d'énergie

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2539817A (en) * 1946-10-31 1951-01-30 Francis J Ditter Aircraft ski
US5211359A (en) * 1991-05-06 1993-05-18 Aerospatiale Societe Nationale Industrielle Landing gear for aerodynes, with crosspieces in composite material
US5358201A (en) * 1993-02-05 1994-10-25 Brown Sr Louis S Vehicle skid assembly
US5462242A (en) * 1993-11-05 1995-10-31 Bell Helicopter Textron Inc. Helicopter landing gear assembly

Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US6244538B1 (en) * 1999-05-19 2001-06-12 Bell Helicopter Textron Inc. Stiffness de-coupled skid landing gear
US6427942B2 (en) * 1999-05-19 2002-08-06 Bell Helicopter Textron Inc. Stiffness de-coupled skid landing gear
US20150336661A1 (en) * 2012-06-26 2015-11-26 Bell Helicopter Textron Inc. Lightweight helicopter skid shoes
US9676476B2 (en) * 2012-06-26 2017-06-13 Bell Helicopter Textron Inc. Lightweight helicopter skid shoes
US10858091B2 (en) 2017-08-11 2020-12-08 Bell Helicopter Textron Inc. Helicopter skid landing gear

Also Published As

Publication number Publication date
WO1997035762A1 (fr) 1997-10-02
CA2222184A1 (fr) 1997-10-02
DE69705786D1 (de) 2001-08-30
ATE203478T1 (de) 2001-08-15
CA2222184C (fr) 2002-03-12
AU2019697A (en) 1997-10-17
DE69705786T2 (de) 2002-05-08
EP0828655A1 (fr) 1998-03-18
EP0828655B1 (fr) 2001-07-25

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